Abstract

Mood conditions comprise several different entities. At the very end of the nineteenth century (1899), German psychiatrist E. Kraepelin established what he called “manic-depressive illness,” a broad clinical concept based on course and outcome for mood illnesses. Inside this entity, there was room for several different clinical presentations (ranging from euphoric manic phases to melancholic depressive phases). Kraepelin offered a dimensional approach to mood conditions with no clear bounds between all of them. In the late 1950s (1957), there was an effort to make a categorical distinction between unipolar and bipolar depression, led by German psychiatrist K. Leonhard. This approach was leaning toward a more “cut and clear” categorical differentiation between these conditions. Current psychiatric classification systems (DSM and ICD) are more attached to Leonhard’s views, posing the categorical distinction between bipolar and unipolar mood conditions as the current state of the art. In recent years mood researchers developed the concept of “mood spectrum,” (N Ghaemi, J Angst). This new development sought to bring back Kraepelin’s view, recognizing that mood diseases do not behave as categorical entities but rather as clinical presentations inside a dimensional concept. Clinical features, such as number of previous episodes, familiality, and treatment response, are considered as clinical validators of the spectrum. This last nosological development has shown tremendous treatment implications. The most important of these implications is related to the fact that antidepressants remain as the most used drug for bipolar disorders, mostly by under recognition of the disease, giving to bipolar patients the likelihood of manic switch or mood destabilization. In fact, a more dimensional approach seeks to help clinicians in making the subtle distinction between bipolar disorder and other mood conditions.